Requirements for electrostatic grounding of piping systems
2022-04-30 0 By
SHT3097 piping system should be grounded at the inlet and outlet area (including workshop building) and branch.Long distance pipes should be grounded at the beginning, end, branch and every 100m.If the net distance between parallel pipes is less than 100mm, add jumper cables every 20m.When the pipelines cross and the net distance is less than 100mm, jumper wiring should be added.When metal flanges are fastened by metal bolts or clips, there is generally no need to install another electrostatic connection line, but at least two bolts or clips should be guaranteed to have a good conductive contact surface.When there is an isolation block between the process pipe and the heat tracing pipe (to prevent local overheating and contact corrosion), the heating tracing pipe should not only use metal wires to bind the connection, but also make the steam inlet and water return port of the tracing pipe and the process pipe and other positioning connections.When the protective cover of air duct and insulation layer is made of thin metal plate, it should be bitten and connected by mechanical bolt equipotential.The non-conductor pipe in the middle of the metal pipe should be connected to the grounding main line, or be grounded after being bonded with a copper conductor cable with a cross section of no less than 6mm2, except for special antistatic treatment.All metal parts on the non-conductor pipe section shall be connected to the ground.Static grounding is not required for directly buried metal pipes.SY0060 buried metal pipes without cathodic protection should be grounded statically at the entry point.Pipelines on the ground or in the pipeline trench should meet the following requirements: pipelines should be grounded in the entrance and exit device diagram and the production plant, the boundary and branch with explosion risk, and long-distance pipelines without branches should be grounded every 200~300m.When the net distance between parallel pipes is less than 100mm, it should be bonded every 20m;When the net crossing distance of pipes is less than 100mm, it should be bonded.The flange joints of oil and gas pipelines should be bonded.When not less than five bolts are connected, bonding is not allowed in non-corrosive conditions.Indoor metal pipes and accessories can be grounded through the process equipment for anti-static, and the accessories connected with metal bolts can not be bonded separately.All metal parts on non-conductive pipes should be grounded against static electricity.The grounding connection points of HG20675 pipe network should meet the following requirements: The pipes in each relatively independent building (structure) in the device area can be connected to the metal shell of the process equipment (flange connection) for electrostatic grounding.Grounding points should be set for pumps, filters, and moderators in the pipe network.The pipe network should be grounded at the inlet and outlet of the device, the boundary of different explosive hazardous environments, and the pipe bifurcation. For long-distance pipelines without branches, it should be reliably connected with the grounding body every 80~100m.For the non-conductor pipe segment (such as PVC pipe) in the middle of the metal pipe, except for shielding, the metal pipe at both ends should be connected to the grounding main line respectively, or be connected with 6mm2 multi-strand copper insulated wire and grounded.The metal parts on the non-conductor pipe section shall be connected to the ground.Metal pipe sections used for cathodic protection shall not be grounded for static electricity.The specific method of electrostatic grounding should meet the following requirements :(1) on the pipe wall or pipe support, the connecting end should be set up to connect the pipe or pipe with the grounding branch, trunk line.The fixed support of the pipe can also be used for grounding.(2) Section steel pipe rack can be used as the conductor of the grounding connection system, and the connection end can be welded on the pipe rack.(3) Flexible connection shall be adopted between above-ground and non-directly buried pipelines and grounding branch lines, and bolts shall be fastened.The connecting wire should be 6mm2 multi-strand copper polyvinyl chloride wire with a margin of not less than 100mm in length.(4) The pipes directly buried underground shall use 40x4mm galvanized flat steel as branch lines, and shall be connected with the grounding main lines respectively by welding method.The branch line should be set aside not less than 100mm margin, and plane bending 90°.(5) When the protective cover of air duct and insulation layer is made of thin metal plate, tin welding bite shall be applied, or bolts fixed by machinery shall be connected to each other.The soldering length of metal plate should be greater than 100mm.(6) Between the process pipe and the heating tracing pipe, the steam inlet and water return port of the tracing pipe should be connected with the support of the process pipe in addition to the binding metal wire connection.(7) The cast iron socket tube shall be connected by 25mmX4mm flat steel, tin lined clamp and 6mm2 multi-strand copper polyvinyl chloride wire (25X4mm flat steel).(8) The shielding line of the whole non-conductor pipe can be connected in sections to the metal support of the grounded pipe.All metal parts of the pipe section shall be connected to the nearest grounding bracket or grounding main line.(9) The hose in the pipe network should be used with metal helix or metal protection net as far as possible.Metal helix, metal protection net and metal fittings at both ends of hose should be connected to each other and grounded at one end.Conductive rubber hoses and rigid insulating tubes coated with conductive paint shall be grounded with a tightly bonded metal hoop.GB50235 design of pipes with electrostatic grounding requirements, when the resistance value between each pair of flanges or other joints exceeds 0.03 ohm, should be set up wire jumper.The grounding resistance value, grounding position and connection mode of the piping system should conform to the provisions of the design document.Use welding for electrostatic grounding.Stainless steel and non-ferrous metal pipes with electrostatic grounding requirements, wire jumper or ground lead shall not be directly connected with the pipe, should use the same material connecting plate transition.Do not paint the materials or components used for electrostatic grounding before installation.Conductive contact surfaces should be derusted and tightly connected.After the electrostatic grounding is installed, test it. If the resistance exceeds the specified value, check and adjust it.